1. Field of the Invention
The present invention relates to a heat exchanger, which is installed in a vehicular air conditioning apparatus that performs temperature adjustment of a vehicle compartment, whereby the heat exchanger is used by the vehicular air conditioning apparatus for cooling and heating of air that is blown into the vehicle compartment.
2. Description of the Related Art
In a vehicular air conditioning apparatus that is mounted in a vehicle, internal and external air is drawn into a casing by a blower, and after cooled air, which has been cooled by a heat exchanger that forms a cooling means, and heated air, which has been heated by a heat exchanger that forms a heating means, are mixed together in the casing at a predetermined mixing ratio, the mixed air is blown out from defroster blowout ports, face blowout ports, or foot blowout ports arranged in the vehicle compartment, whereby adjustment of temperature and humidity in the vehicle compartment is carried out. With this type of vehicular air conditioning apparatus, for example, a plurality of ventilation passages through which air flows are included inside the casing, whereby air that flows through certain ones of the ventilation passages is blown out toward the foot blowout ports, whereas air that flows through other of the ventilation passages is blown out toward the defroster blow-out ports and/or the face blow-out ports.
In a vehicular air conditioning apparatus such as described above, for example, as disclosed in Japanese Laid-Open Patent Publication No. 09-104216, so as to correspond respectively with the ventilation passages, partition panels are provided on upstream and downstream sides of the heat exchanger, respectively, so that one and the other of the ventilation passages are separated from each other by the partition panels. Together therewith, by arranging a partition panel in alignment with any one of a plurality of tubes that make up the heat exchanger, airflows that flow respectively through one of the ventilation passages and the other of the ventilation passages are separated from each other inside the heat exchanger.
Notwithstanding, with the aforementioned conventional technique, for example, in the case of being applied to a heat exchanger that includes two layers of tubes, inside the heat exchanger, air tends to pass and flow in an intermingling manner between one set of tubes provided on the front surface side of the heat exchanger and the other set of tubes provided on the rear surface side of the heat exchanger.
Therefore, with a heat exchanger having such a two-layered arrangement of tubes, air which flows through one or the other of the ventilation passages and flows into the heat exchanger tends to flow from a passage in which the air flow rate is abundant, and which is high in pressure, toward the side of a passage in which the air flow rate is smaller and which has a relatively low pressure. As a result, the air inside each of the passages on the downstream side of the heat exchanger does not obtain desired airflow rates, so that ultimately, the mixing ratio between cool air and warm air becomes altered. Also, the air, which is blown out from each of the blow-out ports inside the vehicle compartment, is not capable of achieving a desired temperature and blowing rate.
Further, when the flow of air inside either one of the first or second passage is stopped, air flowing through one of the ventilation passages passes through the interior of the heat exchanger and flows into the other ventilation passage, and such air is blown out into the vehicle compartment. More specifically, blowing out of air continues to be performed unintentionally even from blow-out ports inside the vehicle compartment for which blowing of air has been stopped, thereby imparting a sense of discomfort to passengers in the vehicle compartment.